The subject matter disclosed herein relates to turbines and, more specifically, measuring angular displacement of a rotatable shaft to determine torque.
Various machines, such as a gas turbine and/or a steam turbine, may be used to drive a load such as a power generator. In particular, a gas turbine and/or a steam turbine may be used to rotate a magnet within a stator to generate electric power. The power generator includes a shaft which is connected to the rotating magnet and which itself is connected to a large connecting shaft (also called a load coupling shaft) rotated by one or more turbines. The connecting shaft is typically large and stiff, thereby resulting in very small torsional displacements (strains) when a torque is imposed on the connecting shaft. A measurement of torque transmitted through the connecting shaft is made to determine the power output of the turbines rotating the connecting shaft.
In an example, the torque measurement is determined by sensors or gauges configured to measure angular displacement at selected locations in the shaft. The value of the angular measurement is typically very small, often below 1 degree. Accordingly, improved accuracy for sensors and measurements of the angular displacements and corresponding torque also improve the determination of power output for the turbine.